1. Field of the Invention
This invention relates to an improvement of a woven type frictional material to be used as a winch of a marine machine or a construction machine, a brake lining or a disk pad of an automobile, and so on.
2. Description of the Prior Art
One of existing woven type frictional materials (using cloth as its basic element) is made by preparing cloth which is woven with one or a mixture of asbestos fiber, aramid fiber, glass fiber, rock wool, ceramic fiber, staple fiber, or the like, and by impregnating the cloth with a bituminous material or a synthetic resin such as asphalt, gilsonite, tung oil, etc.
The existing frictional material indicated above, however, involves the following problems because of a fiber or fibers used as the basic element of the cloth:
(1) Among the fibers indicated above, the asbestos fiber was considered to be an optimum frictional material because of its excellent resistance against heat and friction. However, the use thereof has been restricted because it adversely affects human bodies.
(2) The rock wool and the ceramic fiber are physically weak and, during handling, produce much dust which irritates human skin.
(3) The glass fiber is physically strong, but produces dust during handling, like the rock wool and the ceramic fiber.
(4) The staple fiber is not resistant against heat.
Since each of the fibers used as basic elements of existing frictional materials has advantages and disadvantages from different viewpoints, as indicated above, an improvement thereof is strongly desired.